The present invention relates to fifth wheel assemblies, and in particular to an improved kingpin locking mechanism therefor.
Kingpin locking mechanisms for fifth wheel assemblies, such as those disclosed in U.S. Pat. Nos. 2,663,575; 2,982,566; 3,013,815; 3,640,549 and 4,106,793, which are hereby incorporated by reference, are generally known in the art. Such mechanisms include a pair of pivoting jaws which are closed to form a socket in which the kingpin is retained. An adjustment device is provided to vary the angular orientation of the jaws in the closed position to take up slack in the hitch which is caused by wear.
Although prior adjustable locking mechanisms have proved satisfactory in compensating for side-to-side wear in the hitch, they have been less than fully effective in compensating for fore-to-aft wear in the hitch. This results from the fact that as the left-hand and right-hand jaws are pivotally adjusted inwardly at their rearward ends to close more tightly about the kingpin, the fore-to-aft dimension of the socket does not vary substantially. Since a great majority of the wear which occurs in the socket is in the fore-to-aft direction, it would be highly advantageous to provide a mechanism which compensates for both side-to-side and fore-to-aft wear.